Circuit breaker



Dec. 7, 1954 w. A. HABERMANN CIRCUIT BREAKER Filed Feb. 19, 1953INVENTOR. MYZ'Z/yfl United States Patent IRCUI B EAK William A.Habermanu, Detroit, Mich., assignor to BullDog Electric Products Co.,Detroit, Mich., a corporatiou of West "irginia Application February 19,1953, Serial No. 337,705

Claims. (Cl. 200--116) This application relates to circuit breakersgenerally and discloses an improvement in circuit breakers of the typedisclosed in prior Patent 2,385,727, issued September 25', 1945, to E.T. Platz and to that disclosed in Patent 2,611,052, issued September 16,1952, to E. T. Platz and Russell S. Davis. Disclosed in these patents isa novel type circuit breaker having a push button type operation whichis, manually operable successively for opening and closing the circuitbreaker contacts. The breaker is automatically operable for opening thebreaker contacts upon the occurrence of an overload in the load circuitcontaining the breaker. The circuit breaker may have a thermal overloadtype mechanism which includes a bimetal latch member arranged to latchupon an abutment or holding member upon manual actuation of the breakermechanism to closed circuit position and releasable, automatically ormanually, from the holding member when it is desired to move the breakermechanism to open circuit, or contact separated, position. In this typeof circuit breaker the position of the bimetal latch member relative tothe holding member determines the amount of overlap of the latchingportion of the bimetal latch member. This degree of overlap will in turndetermine the amount of warpage which the bimetal latch member willsustain, when subjected to an excessive or overload electric current,before being released from the holding member. It is common commercialpractice to give the circuit breaker a rating, which is the normal: loadcurrent which it is designed to transmit, expressed in amperes. Thebreaker must not only carry the rated load but also must interrupt thecircuit when the overload exceeds a predetermined percentage of therated load, or if the overload exists for a certain time interval,theproblem thus presented is to provide meansfor varying thecharacteristics of the breaker so that it may be made to selectivelyrespond to more than a single set of overload conditions. The problemthus presented mayv besolved by providing means for variation of theamount of overlap of the latch portion of the bimetal latch element ofthe breaker mechanism so that it will automatically interrupt thecircuit when any of several selected predetermined conditions arise.This is accomplished in. the breaker above referred to by the instantinvention which provides a simple structure for adjustment of theoverlap of the latch portion of the bimetal latch element.

The invention is particularly adapted for use with the circuit breakerdisclosed in Patent No. 2,611,052 referred to above.

Therefore, a primary object of the present invention is to provide anovel calibrating arrangement for a circuit breaker.

A further object of the present invention is to provide a calibratingarrangement which utilizes the existing structure of a circuit breaker.

A further object is to provide a calibrating arrangement which isoperable from the exterior of the circuit breaker.

A still further object is to provide a calibrating arrangement which isflexible, inexpensive and easily adapted to a circuit breaker.

These and other features of the invention will become apparent from thedrawings wherein:

Fig. l is an elevational view with the side removed of a circuit breakerin the On or closed contact position.

Fig. 2 is a sectional fragmentary view as if on line 2,696,541 PatentedDec. 7, 1954 ice 2-2 of Fig. 1, showing a portion of the circuit breakermechanism and,

Fig. 3 is a partial sectional view of the circuit breaker mechanism asif on line 3-3 of Fig. 1.

Referring to the drawings (Fig. 1), the circuit breaker as disclosedincludes a casing 10 composed of a suitable dielectric material and abreaker mechanism substantially the same as that shown in Patent2,611,052 referred to above. This breaker mechanism includes a handle oroperator 11 extending through the top wall 12 of the easing 10. Thisoperator 11 is arranged to be manually actuated successively in apush-push manner to move the breaker to the On and Off positions.Disposed beneath operator 11 and having the upper end seated thereinwith the lower end engaged in an abutment in the rear wall of casing 10,is an operator spring 13. Thus, operator spring 13 exerts an outwardbias upon operator 11 for positioning it preparatory to a successivemanual operation. Below operator 11 and arranged to be engaged therebywhen the breaker mechanism is in the Oil circuit position, is atranslator 14. Mounted on the underside of this translator 14 is anambient compensating spring member 15 having a bent-up portion 16 whichextends through a cut-out portion 17 of translator 14. A contactor 18has secured to it as by a rivet 22 a bimetal latch member 19 and iscomprised of a movable contact 20, an intermediate body portion 23, anda tail guide 21. A flexible conductor 34 completes the circuit thenthrough bimetal latch member 19. Rivet 22 extends through a journal (notshown) in the translator 14 thereby securing these elements in a pivotalrelationship and transmitting circuit closing force applied to operator11 through translator 14 to contactor 18. The upper end of bimetal latch19 has a turned down latch portion 23 (Fig. 3) which engages abutment 29formed in translator 14 for holding the breaker mechanism in the Oncircuit position. Disposed in the casing 10 and having a portionextending through the rear wall thereof, is a fixed contact 24. Amainspring 26 has its lower end seated in a recess 25 of casing 10 andits upper end surrounding a spring lug 27 extending from the side of thetail guide 21 of contactor 18. This mainspring 26 has an inward forcecomponent which biases contactor 18 against translator 14 and alsocounterclockwise about rivet 22 to move the mechanism to open circuitposition upon manual or automatic release of bimetal latch member 18from abutment 29 of translator 14. This mainspring 26 also exerts acontact closing bias when it is desired to move the breaker mechanism toclosed circuit position. The inward component forces bimetal latchmember 19 inwardly so that the latch portion 28 of this member willengage behind abutment 29 of support plate 14 when the breaker mechanismis actuated to the closed or On circuit position. Tail guide 21 is alsoresponsive to the inward force of mainspring 26 and is positionedrelative to the translator 14 when the breaker is in the On circuitposition (Figs. 1, 2, 3) by its contact with the bent-in portion 16 ofthe ambient compensating spring member 15. The tail guide 21 and thebimetal latch member 19 being rigidly secured together, the position ofthis bimetal latch member 19 is also determined relative to translator14. The amount of overlap of the latching portion 16 of the bimetallatch member 19 is thus fixed. Because of the resilient nature of theambient compensating spring member 15 the inward deflection of the tailguide 21 is variable resulting in a variable degree of overlap of thelatching portion 28 of the bimetal latch member 19. To accomplish thisvariation, a calibrating screw 31 of suitable insulating material andhaving a necked down portion 32 extending into the lower end ofmainspring 26 and a bearing plate 33 abutting the lower end ofmainspring 26 is inserted into a tapped hole in the lower wall 32 ofcasing 10 (Fig. 1). From the above description it can be seen that aninward or outward movement of calibrating screw 31, (when the circuitbreaker is in the On circuit position), will vary the compression forceof mainspring 26. The inward component of this compression force willdeflect tail guide 21 in its abutting relationship with the bent-inportion 16 of ambient compensating spring member 15 (Fig. 2). As theposition of tail guide 21 is varied, the position of bimetal latchmember 19 is also varied. This variation in turn results in a variationin the amount of overlap of the latch portion 28 (Fig. 3) of bimetallatch member 19 with respect to abutment 29 on translator 14. Once theamount of latch overlap is determined to permit the breaker to open uponthe occurrence of the selected predetermined overload conditions, it isa simple matter to so adjust the calibrating screw to achieve thedesired result.

As noted, also, in the above description, the function of the ambientcompensating spring member is to provide a flexible abutment for thetail guide 21. In circuit breakers not having such ambient compensatingspring member already incorporated therein, a spring member may beinserted between the tail guide 21 and the translator 14 which willprovide the necessary flexibility to permit variance in the latchingoverlap. Thus, the invention is not limited to the particular circuitbreaker as shown in Patent 2,611,052 but is adaptable to many others.

Now having described the invention herein disclosed, reference should behad to the claims which follow in which we claim:

1. In a thermal overload circuit breaker having a fixed contact and amovable contact with a translator arranged to engage and disengage saidmovable contact with said fixed contact, a translator resilient membersecured to said translator, a carrier for said movable contact having abimetal latch member arranged to latch upon said translator uponactuation of said contact carrier to closed circuit position, saidcontact carrier having guide means abutting said translator resilientmember for determining the position of said bimetal latch memberrelative to said translator, a resilient member for providing circuitopening and circuit closing bias for said contact carrier and fordetermining the position of said bimetal latch member relative to saidtranslator, and means abutting said resilient member for varying thebias of said resilient member whereby said circuit breaker may becalibrated for interrupting an electric current under selectedpredetermined conditions.

2. In a thermal overload circuit breaker having a fixed contact and amovable contact with a translator arranged to engage and disengage saidmovable contact with said fixed contact, a translator resilient membersecured to said translator, a carrier for said movable contact having abimetal latch member arranged to latch upon said translator uponactuation of said contact carrier to closed circuit position, saidcontact carrier having guide means abutting said translator resilientmember for determining the position of said bimetal latch memberrelative to said translator, a resilient member for providing circuitopening and circuit closing bias for said contact carrier and fordetermining the position of said bimetal latch member relative to saidtranslator, and adjustable means abutting said resilient member forvarying the bias of said resilient member whereby said circuit breakermay be calibrated for interrupting an electric current under selectedpredetermined conditions.

contact and a movable contact with a translator arranged to engage anddisengage said movable contact with said fixed contact, a translatorresilient member secured to said translator, a carrier for said movablecontact having a bimetal latch member arranged to latch upon saidtranslator upon actuation of said contact carrier to closed circuitposition, said contact carrier having guide means abutting saidtranslator resilient member for determining the position of said bimetallatch member relative to said translator, a resilient member forproviding circuit opening and circuit closing bias for said contactcarrier and for determining the position of said bimetal latch memberrelative to said translator, and screw means abutting said resilientmember for varying the bias of said resilient member whereby saidcircuit breaker may be calibrated for interrupting an electric currentunder selected predetermined conditions.

4. In a thermal overload circuit breaker having a fixed contact and amovable contact with a translator arranged to engage and disengage saidmovable contact with said fixed contact, a resilient ambientcompensating member secured to said translator, a carrier for saidmovable contact having a bimetal latch member arranged to latch uponsaid translator upon actuation of said contact carrier to closed circuitposition, said contact carrier having guide means abutting saidresilient ambient compensating member for determining the position ofsaid bimetal latch member relative to said translator, a resilientmember for providing circuit opening and circuit closing bias for saidcontact carrier and for determining the position of said bimetal latchmember relative to said translator, and means abutting said resilientmember for varying the bias of said resilient member whereby saidcircuit breaker may be calibrated for interrupting an electric currentunder selected predetermined conditions.

5. In a thermal overload circuit breaker having a fixed contact and amovable contact with a translator arranged to engage and disengage saidmovable contact with said fixed contact, a translator resilient membersecured to said translator, a carrier for said movable contact having abimetal latch member arranged to latch upon said translator uponactuation of said contact carrier to closed circuit position, saidcontact carrier having guide means abutting said translator resilientmember for determining the position of said bimetal latch memberrelative to said translator, a resilient member for providing circuitopening and circuit closing bias for said contact carrier and fordetermining the position of said bimetal latch member relative to saidtranslator, said guide means being adjustably positioned by saidtranslator resilient member to enable said circuit breaker to becalibrated to interrupt an electric current upon the occurrence ofselected predetermined conditions.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,035,743 Frank et al. Mar. 31, 1936 2,049,354 Chapman July28, 1936 2,132,628 Jackson Oct. 11, 1938

